In the rubber industry, rubber products such as vehicle tires and seals are made typically by compounding a mixture of fillers, such as carbon black or silica in rubber, which is then vulcanized. For vehicle tires, additional structural properties are introduced by embedding cords and by using different types of rubber in the tread, side-wall, and interior lining.
The manufacturer of rubber materials, such as a tire manufacturer, typically receives a raw material from different sources. Rubber is received in bales or possibly as a crumb or a powder. In making the rubber, filler materials such as carbon black are used.
The carbon black that is most desirable for use as a filler in rubber compounds such as tires, in its original state is called fluffy carbon black. Then it is pelletized or mixed in a slurry. Fluffy carbon black is carbon black agglomerates that consist of fine particles or agglomerates that are measured in nanometers (nm) and have a very low bulk density. There are several processes for making carbon black, including an oil furnace process. The oil furnace process essentially pyrolyses the oil to produce pure carbon particles often referred to as virgin carbon black. More recently there has been greater interest in producing and or reclaiming carbon blacks, including fluffy carbon black, from used rubber products such as scrap tires. Such processes essentially allow for the carbon black fillers to be extracted or recovered from the used rubber products and recycled back into new rubber products as filler materials.
There have been many attempts to recycle tires and other rubber products to reclaim usable hydrocarbons through the use of a process called pyrolysis. Through pyrolysis, tires and other oil based compounds are processed to produce fuel and other hydrocarbon compounds. One particular byproduct resulting from the pyrolysis process is a carbonaceous ash or char material which is leftover after the process is complete. Attempts have been made to use this char as a low grade carbon black for use as a type of filler. However, this has been met with several disadvantages, most significantly the disadvantage of the impurities in the char resulting from the random distribution of particle size of the char as well as unwanted impurities such as ash. Additionally the surface chemistry of the particles has an effect on the ability of the carbon black material to be used as a filler material and some of the past attempts have yielded black carbon agglomerate particles having unfavorable surface chemistry. Thus there exists a need to provide reclaimed carbonaceous mixtures that are suitable for use as a high grade filler material comparable to virgin carbon black material.